How can we determine this fact? Its because Bristol commuters, including the driver of the green Renault Clio S540NTP and Silver Ford focus Y506TGV are all law abiding citizens of the city. They would no more park illegally than they would speed down a road without cameras.
If they were parked illegally, they would be ticketed -and as they are not, even when they park here, day after day, they can be confident that this is in fact a legitimate activity.